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Old 04-13-2005, 05:08 PM   #16
Darkness95m3
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Quote:
Originally Posted by windwagen
I'm tired of HP ratings...You know what I mean...a 280HP V6 that can't do any better than 7 sec 0-60. Or a 200HP motor that feels slightly faster than a shopping cart!

Those who know, realize that a motor's true output is the AREA under the curve on a dyno graph.

We need a new standard...Can we call it useable HP, or Useable torque? This would consider output over a range of engine speeds, not just the peak.

What should the units be? HPxRPM?? ft.lbxRPM?
Look at what you started ...
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Old 04-17-2005, 08:38 AM   #17
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Originally Posted by Ant118
Well u wanna here something really sad my father was driving his 1998 M3 and some kid in his Neon SRT-4 pulled up beside him and wanted to race so my father hammers it and the kid hammers it and the F***in Neon smoked him, no my father now how to drive he used to race. So this is really starting to piss me off cause now these little friggin neons and now the Cobalt SS is beating our cars that we thought we amazing, dont get me wrong the M3 will smoke it on the track like braking and turning but on the straight and off the line where gone
Don't have to feel bad - the SRT-4 Neons are fast cars. They can be easily modded to really create some power.
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Old 04-17-2005, 10:57 AM   #18
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Quote:
Originally Posted by Ant118
Well u wanna here something really sad my father was driving his 1998 M3 and some kid in his Neon SRT-4 pulled up beside him and wanted to race so my father hammers it and the kid hammers it and the F***in Neon smoked him, no my father now how to drive he used to race. So this is really starting to piss me off cause now these little friggin neons and now the Cobalt SS is beating our cars that we thought we amazing, dont get me wrong the M3 will smoke it on the track like braking and turning but on the straight and off the line where gone
At end of the day you are still driving a BMW. By the way I'm not making fun of the other vehicles.
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Old 04-17-2005, 12:10 PM   #19
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I say it has a lot to do with gearing. Gearing is just a torque multiplier right.
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Old 04-17-2005, 04:25 PM   #20
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Quote:
Originally Posted by windwagen
I'm tired of HP ratings...You know what I mean...a 280HP V6 that can't do any better than 7 sec 0-60. Or a 200HP motor that feels slightly faster than a shopping cart!

Those who know, realize that a motor's true output is the AREA under the curve on a dyno graph.

We need a new standard...Can we call it useable HP, or Useable torque? This would consider output over a range of engine speeds, not just the peak.

What should the units be? HPxRPM?? ft.lbxRPM?
Ok, time to ask a stupid question, but what kind of engineer are you? If you're stating that HP is a meaningless number, but you then ask if ft.lbs x RPM should be the standard? Uh...hate to break it to you, but that is 2/3 rds of the definition of HP. Degree in engineering what what university? Tony the Tiger's?

Also, you idea that a car that makes 270 HP from 3000 to 6000 RPM doesn't work. That would mean that the torque output of the motor is constantly dropping from 3000 RPM to 6000 RPM; not something that you want.

A better idea is a broad, flat torque curve, but this is simply engine design, and has little to do with overall performance of the car. Numerous other factors apply, not the least of which is the weight of the car. A 2500 lb car putting out 200 HP is going to be quicker than a 3500 lb car putting out 250 HP. Gearing etc, will all apply, but you also have to consider what top speed you expect to run at as well.

A high revving, low torque motor (think Hayabusa, or the 2.0L from the S2000) is more effective at higher RPMs, and ultimately moreso at higher speeds. If the races is from 0-30 MPH, then the high torque, low RPM car wins. If the race is from 60-90 MPH, then the high RPM, low torque car may likely win, even if the HP ratings are similar (think the S2000 vs E36 M3; both with 240 HP, but vastly different torque curves).

Each time you shift gears, you're exchanging available torque for speed. If your redline is 9,000 RPM, you suddenly have that much more RPM headroom to accelerate in; headroom that the E36 doesn't have. So stoplight to stoplight, the E36 M3 might be quicker. In a quarter mile (or half mile), the S2000 might be quicker.

Also, once you breach the 100 MPH mark, aerodynamics start to play a huge part. And you need HP to get over the aerodynamic barriers that you may encounter.

Torque by itself is only an instantaneous measure of the work being done; HP is a measure of the ability to do work over time.

Unless you're building race motors, I wouldn't worry too much about the area under the curve; in a street car, it's nearly meaningless, compared to far more important characteristics to base a buying decision on.


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Old 04-17-2005, 08:06 PM   #21
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Quote:
Originally Posted by GR8 Ride
Ok, time to ask a stupid question, but what kind of engineer are you? If you're stating that HP is a meaningless number, but you then ask if ft.lbs x RPM should be the standard? Uh...hate to break it to you, but that is 2/3 rds of the definition of HP. Degree in engineering what what university? Tony the Tiger's?




Pat
Uhhh. That's just nasty!

And uh what's wrong with Tony the Tiger University?
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Old 04-19-2005, 12:57 AM   #22
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Pat beat me to the RPM * lb.ft.

When I read about what other ways to measure the power curve. I instantly thought rms power. But seeing that the power curve is only a single cycle means HP(rms) would only give a numeric indicator again. I like the ara under the curve thing, but then again its still dumb since no uses the top 1/3 or the rpm band every day anyways.

I would suggested a wieghted area under the curve result instead. Or maybe some kind of gaussian curve for the wieghting of the rpms under the hp vs rpm curve.

I'll shut up now and get back to studying. At this point im up for discussing anything to get outta studying.
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Old 04-19-2005, 10:14 AM   #23
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I just think we should Give Up.
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Old 04-21-2005, 11:42 PM   #24
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Pat,

What I mean is ....the PEAK Hp number only tells part of the story.

I have to disagree about the area under the curve being important for a race motor. A motor with HP at high rpm is better suited for a track. For daily drivers, lots of torque is more desireable.

And the showroom is exactly where the HP specs are most misrepresented. Marketing HP numbers!!
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Last edited by windwagen; 04-21-2005 at 11:49 PM.
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Old 04-22-2005, 09:22 AM   #25
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Quote:
Originally Posted by windwagen
Pat,

What I mean is ....the PEAK Hp number only tells part of the story.

I have to disagree about the area under the curve being important for a race motor. A motor with HP at high rpm is better suited for a track. For daily drivers, lots of torque is more desireable.

And the showroom is exactly where the HP specs are most misrepresented. Marketing HP numbers!!
Uhh....race many cars? WTF do you mean, the 'area under the curve isn't important for a race motor"? Again, I have to ask, "race many cars?"

True, peak HP does only tell part of the story, but usable torque applies to both a street car, AND a race car. I have no idea where you think a usable torque curve doesn't apply to a race motor. Go spend sometime behind the wheel of a racecar, and you'll see what I mean.


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Old 04-22-2005, 09:50 AM   #26
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Quote:
Originally Posted by GR8 Ride
Unless you're building race motors, I wouldn't worry too much about the area under the curve; in a street car, it's nearly meaningless, compared to far more important characteristics to base a buying decision on.


Pat
Pat,

Not that it's not important for race motors, I disagreed with your "statement" suggesting Area Under Curve being important for race motors ONLY. Sorry, left out the word.

I don't like to be picky, but your latest post supports the above.
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Old 04-22-2005, 11:38 AM   #27
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And for a street car, I have far more important things to worry about than the area under the curve.

If you're basing your buying decisions based upon "area under the curve", then you may as well buy a truck, as a big torque V-8 or V-10 is going to have the largest "area under the curve". My point was simply in stating that "area under the curve" is a minor concern when buying a street car. A simple test drive would demonstrate just how suitable the car is for daily driving (ie, how much grunt does the car really have...).

For day to day driving, how often does someone really use all of their "area under the curve"? Precious little.

Dyno charts and "area under the curve" is good for bragging rights on street cars, but is essentially otherwise meaningless.



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Old 04-22-2005, 03:57 PM   #28
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lets not forget vehicle weight as it plays a huge role in acceleration.

every 10 pounds you loose translates to about 1 hp gain. So a vehicle that weighs 300 lbs less translates to having about 30 hp more.

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Old 04-22-2005, 04:26 PM   #29
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having linear power is only good for pick up and go. For instance you have a long powerband 3-5K is one flat peak. Well when your driving you can stomp on the gas in any gear @3-5K and you`ll accelerate just the same. This would be awsome for city driving, and awsome for running around cones at a local autocrossing event.

its not however great for drags, or real racing etc

When your racing your in the top part of your RPM band, so you want 5-7k(as an example) rather then 3-5k. Gearing does make a huge diff and so will torque. But if you have a car thats got all top end, little torque your likely to do a faster time then a guy that has the same peak but on a lower and more "FULLER" powerband. Personally i want top end, i dont care about 0-3500rpm cause if im racing i`ll never be in that range, i want to focus on 4-7000 and have a skyrocketing type powerband (something that looks like a ski slope 50deg or more), something that will allow 2nd gear to grip easily.


So if you wanna leave people on the street while driving and take people by suprise - low end, long low power band,

If you wanna go fast on the track - top end, high short powerband
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Old 04-25-2005, 12:19 AM   #30
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Quote:
Originally Posted by GR8 Ride
For day to day driving, how often does someone really use all of their "area under the curve"? Precious little.

Dyno charts and "area under the curve" is good for bragging rights on street cars, but is essentially otherwise meaningless.

Pat
Which part of a dyno curve do most daily drivers use? The bottom half of the RPM range, or the part showing the peak HP??

How about using max HP for bragging rights?
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